Mycoplasma Genitalium Fact File
What is Mycoplasma genitalium?
Mycoplasma genitalium, often shortened to MG or Mgen, is a sexually transmitted infection (STI) that many people haven’t even heard of. Despite being lesser-known than infections like chlamydia or gonorrhoea, it's increasingly recognised as a cause of persistent genital and urinary symptoms. Scientists first discovered the bacterium in the 1980s, but it took several decades for it to be widely acknowledged in sexual health care. Even now, it's not routinely tested for in all clinics, partly because of how tricky it is to detect and treat.
So what exactly is it? MG is a microscopic bacterium that lives in the lining of the genital and urinary tracts. It's particularly stubborn because it lacks a cell wall, the structure many common antibiotics target. This makes treatment complicated and resistance more likely. Infections can linger without noticeable symptoms, quietly causing inflammation and, in some cases, longer-term complications.
While MG can affect anyone who is sexually active, it's more commonly found in people under the age of 25 and those with new or multiple sexual partners. According to the British Association for Sexual Health and HIV (BASHH), MG may affect 1 to 2% of the general population, though prevalence is higher in people attending sexual health clinics.
Because MG doesn't always cause symptoms, many people won't know they have it until a partner is diagnosed or until symptoms appear and persist. That delayed onset can allow it to spread unknowingly, which is a key reason public awareness is so important.
Symptoms of Mycoplasma genitalium
Here’s one of the more frustrating things about MG: in many people, it causes no symptoms at all. When symptoms do show up, they can be subtle or mimic other, more well-known infections, such as chlamydia. This can lead to misdiagnosis or ineffective treatment.
Most symptoms, when they do occur, are related to inflammation. The infection affects the urethra, cervix, or reproductive organs, depending on the individual. Common symptoms for both men and women include:
- Pain or burning when urinating
- Genital discharge (which may be watery or slightly cloudy)
- Discomfort during or after sex
- Spotting or bleeding between periods (in women)
- Lower abdominal pain
Some people might experience only one of these, or none at all. Others may suffer ongoing symptoms that don’t resolve even after a course of antibiotics. This is often what leads clinics to suspect MG in the first place.
Persistent or recurring symptoms, especially when other infections have been ruled out – are a red flag. In these cases, testing for MG may be recommended.
Symptoms in Women
For women, the symptoms of MG can be especially hard to identify because they often resemble those of other conditions. Some women notice a change in vaginal discharge, while others experience bleeding after sex or between periods. Occasionally, there may be pelvic discomfort or pain during intercourse.
Common symptoms include:
- Unusual vaginal discharge
- Pain during or after sex
- Bleeding between periods or after sex
- Pain or burning when passing urine
- Lower abdominal or pelvic pain
Because these symptoms overlap significantly with chlamydia, many women are first treated with standard antibiotics aimed at chlamydia or gonorrhoea. If symptoms persist, doctors may investigate further and test for MG.
Left untreated, MG in women can lead to more serious complications like pelvic inflammatory disease (PID). PID can cause lasting damage to reproductive organs, increasing the risk of infertility or ectopic pregnancy. The tricky part is that PID can develop without dramatic symptoms, especially in its early stages.
For this reason, it’s crucial to follow up on any unusual or persistent symptoms, even if they seem mild. Early intervention can prevent more serious issues later.
Symptoms in Men
In men, MG tends to target the urethrathe tube that carries urine and semen out of the body. The result is often a condition called urethritis, which simply means inflammation of the urethra.,
The key symptoms to watch out for include:
- Pain or burning when urinating
- Watery or cloudy discharge from the penis
- Itching or irritation inside the urethra
- Discomfort during ejaculation or after sex
- Pain or swelling in the testicles (less common)
Again, these symptoms might sound familiar. They mirror those of chlamydia and gonorrhoea, which is why MG is often only tested for when other STI tests come back negative and symptoms continue.
In more advanced or untreated cases, MG can lead to complications like epididymitis – an inflammation of the tube that stores and carries sperm. This condition can be quite painful and, if untreated, may impact fertility.
If you've had symptoms like these that don’t clear up after treatment, it’s important to return to the clinic. Further testing could reveal MG as the underlying cause.
Treatment for Mycoplasma genitalium
Treating MG is far more complicated than it used to be. A decade ago, a single dose of azithromycin might have done the job. Unfortunately, due to rising antibiotic resistance, those days are over.
These days, treatment often involves a combination of antibiotics, starting with a course of doxycycline. This helps to reduce the number of bacteria. After that, depending on the results of resistance testing, a second antibiotic like azithromycin or moxifloxacin is prescribed.
Here’s what typical treatment might look like:
- Doxycycline (100mg twice daily for 7 days)
-
Follow up antibiotic, either:
- Azithromycin over several days
- Moxifloxacin (if resistance is detected or suspected)
Testing for resistance is crucial, though not always available at every clinic. Where possible, it helps guide treatment and avoid giving antibiotics that are unlikely to work.
A test of cure is often recommended 3–5 weeks after treatment to make sure the infection has cleared. During treatment, and until you're confirmed to be clear, it's advised to avoid all sexual contact.
How to Avoid Getting and Spreading Mycoplasma genitalium
Prevention is always better than cure, and when it comes to MG, this is particularly true. Given the challenges of treatment and the growing problem of resistance, it’s worth taking steps to protect yourself and your partners.
Here are some practical tips:
- Use condoms consistently during vaginal and anal sex. MG spreads through genital contact, so barrier protection helps a lot
- Get tested regularly, especially if you have new or multiple sexual partners
- Avoid sex if you or your partner have symptoms until both of you have been checked and, if needed, treated
- Tel your sexual partners if you've been diagnosed. They may need testing and treatment too
- Don't rely solely on symptoms. Since MG often causes none, regular check-ups are key
Unlike some other infections, MG doesn’t appear to be spread via kissing, sharing towels, or toilet seats. It is, however, stubborn. And if both partners aren’t treated, it can bounce back and forth even after one course of antibiotics.
Complications of Mycoplasma genitalium
When caught early and treated properly, MG can usually be cleared without long-term problems. But if it’s left untreated, especially when symptoms are mild or absent – it can cause damage over time.
For women, the biggest risk is pelvic inflammatory disease (PID). PID can lead to:
- Scarring of the Fallopian tubes
- Infertility
- Chronic pelvic pain
- Ectopic pregnancy (where the fertilised egg impants outside the womb)
For men, complications are less common but still possible. MG can cause:
- Epididymitis (inflammation of the epididymis)
- Reduced sperm quality in some cases
There’s also growing concern that MG may increase the risk of contracting or passing on HIV. While the evidence isn’t definitive, the inflammation MG causes may make the genital tract more vulnerable to other infections.
These potential complications highlight the importance of regular sexual health screenings and following up on persistent symptoms, even if they’re mild or vague.
Mycoplasma genitalium in Pregnancy
MG during pregnancy adds another layer of concern. The infection has been linked to a higher risk of:
- Miscarriage
- Preterm birth
- Premature repture of membranes
- Low birth weight
The research is still ongoing, and while not all pregnancies with MG result in complications, the risks are enough that it’s taken seriously.
If you’re pregnant and test positive for MG, your doctor or midwife will consider treatment options carefully. Not all antibiotics used for MG are safe in pregnancy, so the decision will be based on the stage of pregnancy and the severity of infection.
In some cases, treatment might be delayed until after the first trimester. In others, the benefits of clearing the infection may outweigh the risks of using certain antibiotics. Close monitoring is key, and you should feel encouraged to ask as many questions as needed to understand the plan.
Partners may also need to be tested and treated, to prevent reinfection during pregnancy.
While Mycoplasma genitalium might not be as well-known as other STIs, it’s no less important. The quiet nature of the infection, coupled with increasing antibiotic resistance, means awareness and prevention are more crucial than ever.
If you’re sexually active, especially with new or multiple partners, regular STI testing and open communication are vital. And if you ever notice symptoms that don't seem to go away, it’s worth returning to your clinic and asking whether MG might be the cause.
As always, early detection, timely treatment, and informed prevention are your best defences.
